1
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Krantz BA. Anthrax Toxin: Model System for Studying Protein Translocation. J Mol Biol 2024; 436:168521. [PMID: 38458604 DOI: 10.1016/j.jmb.2024.168521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/08/2024] [Accepted: 03/04/2024] [Indexed: 03/10/2024]
Abstract
Dedicated translocase channels are nanomachines that often, but not always, unfold and translocate proteins through narrow pores across the membrane. Generally, these molecular machines utilize external sources of free energy to drive these reactions, since folded proteins are thermodynamically stable, and once unfolded they contain immense diffusive configurational entropy. To catalyze unfolding and translocate the unfolded state at appreciable timescales, translocase channels often utilize analogous peptide-clamp active sites. Here we describe how anthrax toxin has been used as a biophysical model system to study protein translocation. The tripartite bacterial toxin is composed of an oligomeric translocase channel, protective antigen (PA), and two enzymes, edema factor (EF) and lethal factor (LF), which are translocated by PA into mammalian host cells. Unfolding and translocation are powered by the endosomal proton gradient and are catalyzed by three peptide-clamp sites in the PA channel: the α clamp, the ϕ clamp, and the charge clamp. These clamp sites interact nonspecifically with the chemically complex translocating chain, serve to minimize unfolded state configurational entropy, and work cooperatively to promote translocation. Two models of proton gradient driven translocation have been proposed: (i) an extended-chain Brownian ratchet mechanism and (ii) a proton-driven helix-compression mechanism. These models are not mutually exclusive; instead the extended-chain Brownian ratchet likely operates on β-sheet sequences and the helix-compression mechanism likely operates on α-helical sequences. Finally, we compare and contrast anthrax toxin with other related and unrelated translocase channels.
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Affiliation(s)
- Bryan A Krantz
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, 650 W. Baltimore Street, Baltimore, MD 21201, USA.
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2
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Perini DA, Aguilella-Arzo M, Alcaraz A, Perálvarez-Marín A, Queralt-Martín M. Dynorphin A induces membrane permeabilization by formation of proteolipidic pores. Insights from electrophysiology and computational simulations. Comput Struct Biotechnol J 2022; 20:230-240. [PMID: 35024095 PMCID: PMC8718563 DOI: 10.1016/j.csbj.2021.12.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/13/2021] [Accepted: 12/13/2021] [Indexed: 01/14/2023] Open
Abstract
Dynorphins are endogenous neuropeptides that function as ligands for the κ-opioid receptor. In addition to opioid activity, dynorphins can induce several pathological effects such as neurological dysfunctions and cell death. Previous studies have suggested that Dynorphin A (DynA) mediates some pathogenic actions through formation of transient pores in lipid domains of the plasma membrane. Here, we use planar bilayer electrophysiology to show that DynA induces pore formation in negatively charged membranes. We find a large variability in pore conformations showing equilibrium conductance fluctuations, what disregards electroporation as the dominant mechanism of pore formation. Ion selectivity measurements showing cationic selectivity indicate that positive protein charges of DynA are stabilized by phosphatidyl serine negative charges in the formation of combined structures. We complement our study with computational simulations that assess the stability of diverse peptide arrangements in the hydrophobic core of the bilayer. We show that DynA is capable of assembling in charged membranes to form water-filled pores that conduct ions.
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Affiliation(s)
- D Aurora Perini
- Laboratory of Molecular Biophysics. Department of Physics. Universitat Jaume I, 12071 Castellón, Spain
| | - Marcel Aguilella-Arzo
- Laboratory of Molecular Biophysics. Department of Physics. Universitat Jaume I, 12071 Castellón, Spain
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics. Department of Physics. Universitat Jaume I, 12071 Castellón, Spain
| | - Alex Perálvarez-Marín
- Biophysics Unit, Department of Biochemistry and Molecular Biology, School of Medicine, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain.,Institute of Neuroscience, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
| | - María Queralt-Martín
- Laboratory of Molecular Biophysics. Department of Physics. Universitat Jaume I, 12071 Castellón, Spain
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3
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Shahedi A, Bolorizadeh MA, Karimi-Maleh H. A europium (III) complex tested for deoxyribonucleic acid-binding, bovine serum albumin binding, and antibacterial activity. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116323] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Liu W, Nestorovich EM. Anthrax toxin channel: What we know based on over 30 years of research. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183715. [PMID: 34332985 DOI: 10.1016/j.bbamem.2021.183715] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Protective antigen channel is the central component of the deadly anthrax exotoxin responsible for binding and delivery of the toxin's enzymatic lethal and edema factor components into the cytosol. The channel, which is more than three times longer than the lipid bilayer membrane thickness and has a 6-Å limiting diameter, is believed to provide a sophisticated unfoldase and translocase machinery for the foreign protein transport into the host cell cytosol. The tripartite toxin can be reengineered, one component at a time or collectively, to adapt it for the targeted cancer therapeutic treatments. In this review, we focus on the biophysical studies of the protective antigen channel-forming activity, small ion transport properties, enzymatic factor translocation, and blockage comparing it with the related clostridial binary toxin channels. We address issues linked to the anthrax toxin channel structural dynamics and lipid dependence, which are yet to become generally recognized as parts of the toxin translocation machinery.
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Affiliation(s)
- Wenxing Liu
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave, Washington, DC 20064, USA.
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5
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VDAC Gating Thermodynamics, but Not Gating Kinetics, Are Virtually Temperature Independent. Biophys J 2020; 119:2584-2592. [PMID: 33189678 DOI: 10.1016/j.bpj.2020.10.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 10/06/2020] [Accepted: 10/16/2020] [Indexed: 12/17/2022] Open
Abstract
The voltage-dependent anion channel (VDAC) is the most abundant protein in the mitochondrial outer membrane and an archetypical β-barrel channel. Here, we study the effects of temperature on VDAC channels reconstituted in planar lipid membranes at the single- and multichannel levels within the 20°C to 40°C range. The temperature dependence of conductance measured on a single channel in 1 M KCl shows an increase characterized by a 10°C temperature coefficient Q10 = 1.22 ± 0.02, which exceeds that of the bathing electrolyte solution conductivity, Q10 = 1.17 ± 0.01. The rates of voltage-induced channel transition between the open and closed states measured on multichannel membranes also show statistically significant increases, with temperatures that are consistent with activation energy barriers of ∼10 ± 3 kcal/mol. At the same time, the gating thermodynamics, as characterized by the gating charge and voltage of equipartitioning, does not display any measurable temperature dependence. The two parameters stay within 3.2 ± 0.2 elementary charges and 30 ± 2 mV, respectively. Thus, whereas the channel kinetics, specifically its conductance and rates of gating response to voltage steps, demonstrates a clear increase with temperature, the conformational voltage-dependent equilibria are virtually insensitive to temperature. These results, which may be a general feature of β-barrel channel gating, suggest either an entropy-driven gating mechanism or a role for enthalpy-entropy compensation.
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Zhang J, Balsbaugh JL, Gao S, Ahn NG, Klinman JP. Hydrogen deuterium exchange defines catalytically linked regions of protein flexibility in the catechol O-methyltransferase reaction. Proc Natl Acad Sci U S A 2020; 117:10797-10805. [PMID: 32371482 PMCID: PMC7245127 DOI: 10.1073/pnas.1917219117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human catechol O-methyltransferase (COMT) has emerged as a model for understanding enzyme-catalyzed methyl transfer from S-adenosylmethionine (AdoMet) to small-molecule catecholate acceptors. Mutation of a single residue (tyrosine 68) behind the methyl-bearing sulfonium of AdoMet was previously shown to impair COMT activity by interfering with methyl donor-acceptor compaction within the activated ground state of the wild type enzyme [J. Zhang, H. J. Kulik, T. J. Martinez, J. P. Klinman, Proc. Natl. Acad. Sci. U.S.A. 112, 7954-7959 (2015)]. This predicts the involvement of spatially defined protein dynamical effects that further tune the donor/acceptor distance and geometry as well as the electrostatics of the reactants. Here, we present a hydrogen/deuterium exchange (HDX)-mass spectrometric study of wild type and mutant COMT, comparing temperature dependences of HDX against corresponding kinetic and cofactor binding parameters. The data show that the impaired Tyr68Ala mutant displays similar breaks in Arrhenius plots of both kinetic and HDX properties that are absent in the wild type enzyme. The spatial resolution of HDX below a break point of 15-20 °C indicates changes in flexibility across ∼40% of the protein structure that is confined primarily to the periphery of the AdoMet binding site. Above 20 °C, Tyr68Ala behaves more like WT in HDX, but its rate and enthalpic barrier remain significantly altered. The impairment of catalysis by Tyr68Ala can be understood in the context of a mutationally induced alteration in protein motions that becomes manifest along and perpendicular to the primary group transfer coordinate.
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Affiliation(s)
- Jianyu Zhang
- Department of Chemistry, University of California, Berkeley, CA 94720
- The California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
| | - Jeremy L Balsbaugh
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309
| | - Shuaihua Gao
- Department of Chemistry, University of California, Berkeley, CA 94720
- The California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
| | - Natalie G Ahn
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309;
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309
| | - Judith P Klinman
- Department of Chemistry, University of California, Berkeley, CA 94720;
- The California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
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7
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Weinrich M, Worcester DL, Bezrukov SM. Lipid nanodomains change ion channel function. NANOSCALE 2017; 9:13291-13297. [PMID: 28858358 PMCID: PMC5599369 DOI: 10.1039/c7nr03926c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Signaling proteins and neurotransmitter receptors often associate with saturated chain and cholesterol-rich domains of cell membranes, also known as lipid rafts. The saturated chains and high cholesterol environment in lipid rafts can modulate protein function, but evidence for such modulation of ion channel function in lipid rafts is lacking. Here, using raft-forming model membrane systems containing cholesterol, we show that lipid lateral phase separation at the nanoscale level directly affects the dissociation kinetics of the gramicidin dimer, a model ion channel.
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Affiliation(s)
- Michael Weinrich
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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8
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Zhang P, Paszkiewicz E, Wang Q, Sadowska JM, Kitov PI, Bundle DR, Ling CC. Clustering of PK-trisaccharides on amphiphilic cyclodextrin reveals unprecedented affinity for the Shiga-like toxin Stx2. Chem Commun (Camb) 2017; 53:10528-10531. [DOI: 10.1039/c7cc06299k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Amphiphilic cyclodextrin-based PK-glycoarrays show remarkable binding avidity and selectivity for Stx2 in solid phase assay formats.
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Affiliation(s)
- Ping Zhang
- Alberta Glycomics Centre
- Department of Chemistry
- University of Calgary
- Calgary
- T2N 1N4 Canada
| | - Eugenia Paszkiewicz
- Alberta Glycomics Centre
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
| | - Qifang Wang
- Alberta Glycomics Centre
- Department of Chemistry
- University of Calgary
- Calgary
- T2N 1N4 Canada
| | - Joanna M. Sadowska
- Alberta Glycomics Centre
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
| | - Pavel I. Kitov
- Alberta Glycomics Centre
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
| | - David R. Bundle
- Alberta Glycomics Centre
- Department of Chemistry
- University of Alberta
- Edmonton
- T6G 2G2 Canada
| | - Chang-Chun Ling
- Alberta Glycomics Centre
- Department of Chemistry
- University of Calgary
- Calgary
- T2N 1N4 Canada
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9
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Simson P, Jepihhina N, Laasmaa M, Peterson P, Birkedal R, Vendelin M. Restricted ADP movement in cardiomyocytes: Cytosolic diffusion obstacles are complemented with a small number of open mitochondrial voltage-dependent anion channels. J Mol Cell Cardiol 2016; 97:197-203. [PMID: 27261153 DOI: 10.1016/j.yjmcc.2016.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/19/2016] [Indexed: 12/17/2022]
Abstract
Adequate intracellular energy transfer is crucial for proper cardiac function. In energy starved failing hearts, partial restoration of energy transfer can rescue mechanical performance. There are two types of diffusion obstacles that interfere with energy transfer from mitochondria to ATPases: mitochondrial outer membrane (MOM) with voltage-dependent anion channel (VDAC) permeable to small hydrophilic molecules and cytoplasmatic diffusion barriers grouping ATP-producers and -consumers. So far, there is no method developed to clearly distinguish the contributions of cytoplasmatic barriers and MOM to the overall diffusion restriction. Furthermore, the number of open VDACs in vivo remains unknown. The aim of this work was to establish the partitioning of intracellular diffusion obstacles in cardiomyocytes. We studied the response of mitochondrial oxidative phosphorylation of permeabilized rat cardiomyocytes to changes in extracellular ADP by recording 3D image stacks of NADH autofluorescence. Using cell-specific mathematical models, we determined the permeability of MOM and cytoplasmatic barriers. We found that only ~2% of VDACs are accessible to cytosolic ADP and cytoplasmatic diffusion barriers reduce the apparent diffusion coefficient by 6-10×. In cardiomyocytes, diffusion barriers in the cytoplasm and by the MOM restrict ADP/ATP diffusion to similar extents suggesting a major role of both barriers in energy transfer and other intracellular processes.
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Affiliation(s)
- Päivo Simson
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Natalja Jepihhina
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Martin Laasmaa
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Pearu Peterson
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Rikke Birkedal
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Akadeemia Rd 21, 12618 Tallinn, Estonia.
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10
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Bezrukov SM, Nestorovich EM. Inhibiting bacterial toxins by channel blockage. Pathog Dis 2016; 74:ftv113. [PMID: 26656888 PMCID: PMC4830228 DOI: 10.1093/femspd/ftv113] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/15/2015] [Accepted: 11/24/2015] [Indexed: 01/01/2023] Open
Abstract
Emergent rational drug design techniques explore individual properties of target biomolecules, small and macromolecule drug candidates, and the physical forces governing their interactions. In this minireview, we focus on the single-molecule biophysical studies of channel-forming bacterial toxins that suggest new approaches for their inhibition. We discuss several examples of blockage of bacterial pore-forming and AB-type toxins by the tailor-made compounds. In the concluding remarks, the most effective rationally designed pore-blocking antitoxins are compared with the small-molecule inhibitors of ion-selective channels of neurophysiology.
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Affiliation(s)
- Sergey M Bezrukov
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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11
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Kish EA, Granqvist CG, Dér A, Kish LB. Lognormal distribution of firing time and rate from a single neuron? Cogn Neurodyn 2015; 9:459-62. [PMID: 26157518 DOI: 10.1007/s11571-015-9332-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/14/2015] [Accepted: 01/16/2015] [Indexed: 10/24/2022] Open
Abstract
Even a single neuron may be able to produce significant lognormal features in its firing statistics due to noise in the charging ion current. A mathematical scheme introduced in advanced nanotechnology is relevant for the analysis of this mechanism in the simplest case, the integrate-and-fire model with white noise in the charging ion current.
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Affiliation(s)
- Eszter A Kish
- Center for Learning and Memory, 1 University Station, Stop C7000, The University of Texas at Austin, Austin, TX 78712-0805 USA
| | - Claes-Göran Granqvist
- Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, P. O. Box 534, 75121 Uppsala, Sweden
| | - András Dér
- Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, P. O. B. 521, Szeged, 6701 Hungary
| | - Laszlo B Kish
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843-3128 USA
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12
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Gurnev PA, Nestorovich EM. Channel-forming bacterial toxins in biosensing and macromolecule delivery. Toxins (Basel) 2014; 6:2483-540. [PMID: 25153255 PMCID: PMC4147595 DOI: 10.3390/toxins6082483] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/08/2014] [Accepted: 08/08/2014] [Indexed: 12/19/2022] Open
Abstract
To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on "Intracellular Traffic and Transport of Bacterial Protein Toxins", reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, α-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their "second life" in a variety of developing medical and technological applications.
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Affiliation(s)
- Philip A Gurnev
- Physics Department, University of Massachusetts, Amherst, MA 01003, USA.
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13
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Roeder M, Nestorovich EM, Karginov VA, Schwan C, Aktories K, Barth H. Tailored cyclodextrin pore blocker protects mammalian cells from clostridium difficile binary toxin CDT. Toxins (Basel) 2014; 6:2097-114. [PMID: 25029374 PMCID: PMC4113744 DOI: 10.3390/toxins6072097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/16/2014] [Accepted: 06/27/2014] [Indexed: 12/11/2022] Open
Abstract
Some Clostridium difficile strains produce, in addition to toxins A and B, the binary toxin Clostridium difficile transferase (CDT), which ADP-ribosylates actin and may contribute to the hypervirulence of these strains. The separate binding and translocation component CDTb mediates transport of the enzyme component CDTa into mammalian target cells. CDTb binds to its receptor on the cell surface, CDTa assembles and CDTb/CDTa complexes are internalised. In acidic endosomes, CDTb mediates the delivery of CDTa into the cytosol, most likely by forming a translocation pore in endosomal membranes. We demonstrate that a seven-fold symmetrical positively charged β-cyclodextrin derivative, per-6-S-(3-aminomethyl)benzylthio-β-cyclodextrin, which was developed earlier as a potent inhibitor of the translocation pores of related binary toxins of Bacillus anthracis, Clostridium botulinum and Clostridium perfringens, protects cells from intoxication with CDT. The pore blocker did not interfere with the CDTa-catalyzed ADP-ribosylation of actin or toxin binding to Vero cells but inhibited the pH-dependent membrane translocation of CDTa into the cytosol. In conclusion, the cationic β-cyclodextrin could serve as the lead compound in a development of novel pharmacological strategies against the CDT-producing strains of C. difficile.
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Affiliation(s)
- Maurice Roeder
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | | | - Vladimir A Karginov
- Innovative Biologics, Inc., 13455 Sunrise Valley Dr., Suite 200, Herndon, VA 20171, USA.
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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14
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Neundlinger I, Puntheeranurak T, Wildling L, Rankl C, Wang LX, Gruber HJ, Kinne RKH, Hinterdorfer P. Forces and dynamics of glucose and inhibitor binding to sodium glucose co-transporter SGLT1 studied by single molecule force spectroscopy. J Biol Chem 2014; 289:21673-83. [PMID: 24962566 DOI: 10.1074/jbc.m113.529875] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Single molecule force spectroscopy was employed to investigate the dynamics of the sodium glucose co-transporter (SGLT1) upon substrate and inhibitor binding on the single molecule level. CHO cells stably expressing rbSGLT1 were probed by using atomic force microscopy tips carrying either thioglucose, 2'-aminoethyl β-d-glucopyranoside, or aminophlorizin. Poly(ethylene glycol) (PEG) chains of different length and varying end groups were used as tether. Experiments were performed at 10, 25 and 37 °C to address different conformational states of SGLT1. Unbinding forces between ligands and SGLT1 were recorded at different loading rates by changing the retraction velocity, yielding binding probability, width of energy barrier of the binding pocket, and the kinetic off rate constant of the binding reaction. With increasing temperature, width of energy barrier and average life time increased for the interaction of SGLT1 with thioglucose (coupled via acrylamide to a long PEG) but decreased for aminophlorizin binding. The former indicates that in the membrane-bound SGLT1 the pathway to sugar translocation involves several steps with different temperature sensitivity. The latter suggests that also the aglucon binding sites for transport inhibitors have specific, temperature-sensitive conformations.
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Affiliation(s)
- Isabel Neundlinger
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Theeraporn Puntheeranurak
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria, Department of Biology, Faculty of Science, Mahidol University and Nanotec-MU Center of Excellence on Intelligent Materials and Systems, 272 Rama VI, Ratchathewi, Bangkok 10400, Thailand
| | - Linda Wildling
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | | | - Lai-Xi Wang
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, and
| | - Hermann J Gruber
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rolf K H Kinne
- Max Planck Institute of Molecular Physiology, Otto-Hahn Strasse 11, 44227 Dortmund, Germany
| | - Peter Hinterdorfer
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria,
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15
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Jara-Oseguera A, Islas LD. The role of allosteric coupling on thermal activation of thermo-TRP channels. Biophys J 2013; 104:2160-9. [PMID: 23708356 DOI: 10.1016/j.bpj.2013.03.055] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/23/2013] [Accepted: 03/27/2013] [Indexed: 11/29/2022] Open
Abstract
Thermo-transient receptor potential channels display outstanding temperature sensitivity and can be directly gated by low or high temperature, giving rise to cold- and heat-activated currents. These constitute the molecular basis for the detection of changes in ambient temperature by sensory neurons in animals. The mechanism that underlies the temperature sensitivity in thermo-transient receptor potential channels remains unknown, but has been associated with large changes in standard-state enthalpy (ΔH(o)) and entropy (ΔS(o)) upon channel gating. The magnitude, sign, and temperature dependence of ΔH(o) and ΔS(o), the last given by an associated change in heat capacity (ΔCp), can determine a channel's temperature sensitivity and whether it is activated by cooling, heating, or both, if ΔCp makes an important contribution. We show that in the presence of allosteric gating, other parameters, besides ΔH(o) and ΔS(o), including the gating equilibrium constant, the strength- and temperature dependence of the coupling between gating and the temperature-sensitive transitions, as well as the ΔH(o)/ΔS(o) ratio associated with them, can also determine a channel's temperature-dependent activity, and even give rise to channels that respond to both cooling and heating in a ΔCp-independent manner.
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Affiliation(s)
- Andrés Jara-Oseguera
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Stochastic detection of Pim protein kinases reveals electrostatically enhanced association of a peptide substrate. Proc Natl Acad Sci U S A 2013; 110:E4417-26. [PMID: 24194548 DOI: 10.1073/pnas.1312739110] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In stochastic sensing, the association and dissociation of analyte molecules is observed as the modulation of an ionic current flowing through a single engineered protein pore, enabling the label-free determination of rate and equilibrium constants with respect to a specific binding site. We engineered sensors based on the staphylococcal α-hemolysin pore to allow the single-molecule detection and characterization of protein kinase-peptide interactions. We enhanced this approach by using site-specific proteolysis to generate pores bearing a single peptide sensor element attached by an N-terminal peptide bond to the trans mouth of the pore. Kinetics and affinities for the Pim protein kinases (Pim-1, Pim-2, and Pim-3) and cAMP-dependent protein kinase were measured and found to be independent of membrane potential and in good agreement with previously reported data. Kinase binding exhibited a distinct current noise behavior that forms a basis for analyte discrimination. Finally, we observed unusually high association rate constants for the interaction of Pim kinases with their consensus substrate Pimtide (~10(7) to 10(8) M(-1) · s(-1)), the result of electrostatic enhancement, and propose a cellular role for this phenomenon.
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Cyclodextrin derivatives as anti-infectives. Curr Opin Pharmacol 2013; 13:717-25. [PMID: 24011515 DOI: 10.1016/j.coph.2013.08.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 07/05/2013] [Accepted: 08/14/2013] [Indexed: 11/22/2022]
Abstract
Cyclodextrin derivatives can be utilized as anti-infectives with pore-forming proteins as the targets. The highly efficient selection of potent inhibitors was achieved because per-substituted cyclodextrins have the same symmetry as the target pores. Inhibitors of several bacterial toxins produced by Bacillus anthracis, Staphylococcus aureus, Clostridium perfringens, Clostridium botulinum, and Clostridium difficile were identified from a library of ∼200 CD derivatives. It was demonstrated that multi-targeted inhibitors can be found using this approach and could be utilized for the development of broad-spectrum drugs against various pathogens.
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Kong L, Harrington L, Li Q, Cheley S, Davis BG, Bayley H. Single-molecule interrogation of a bacterial sugar transporter allows the discovery of an extracellular inhibitor. Nat Chem 2013; 5:651-9. [DOI: 10.1038/nchem.1695] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 05/24/2013] [Indexed: 11/09/2022]
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